Messaging company Slack Technologies scored a unanimous victory in the U.S. Supreme Court on Thursday, which held that an investor suing over a company stock offering must show he held “registered” securities in the company.

Justice Neil Gorsuch wrote the opinion against investor Fiyyaz Pirani in his class action lawsuit against Slack. The decision overturned a ruling by the U.S. Court of Appeals for the Ninth Circuit that Pirani did not have to show he held “registered” securities, those with more investor protections, to sue under Section 11 of the 1933 Securities Act for an allegedly misleading registration statement.